Personally, I love GPS. I will have one in my cars until the GPS satelites fall from the sky.

Then when they do fall from the sky I'll just pretend my GPS units will still work with a tear in my eye.
I think that the "GPS got me stuck in the boonies" stories happen because folks put total trust in a piece of equipment without knowing how to actually use them properly. "Hey, I just bought me an Abrams tank....let's take her for a spin!"
On the two Garmin Nuvis I have there are two main road navigation calculation modes that the user can set up. "Faster Time", "Shortest Distance". The "shorter distance" setting is probably what is putting these folks out in the middle of a forestry road. If the GPS sees "any" kind of road in memory it will calculate a route that way. "Faster Time" will keep you on larger (paved) roadways.
There will also be mistakes with the map data from time to time. You have to consider that most map data was aquired from the US government. They've never made a boo-boo, have they.
Also. Most of the new Garmin car units have a few life saving features. One would be the ability to record "trails" or "tracks'. If the tracking is turned on the GPS records a breadcrumb trail of everywhere you've been. Say a route has taken you deep into national forest and it's looking rough? Just folow your breadcrumbs back out and try another route. Another nice feature is "Where AM I". If you are stuck and can get emergency services on the phone, that feature will allow you to tell SAR your exact coordinates.